ButtonSoup is a lightweight tool for making color themes. It can be experimented in it's current state on https://buttonsoup.xyz
The tool is based on a single CSS file with a relative color system, mathematically expends a single color value fed into it into a modifiable, yet fully functional palette. The style.css file can be downloaded and used as is in any project, with no Javascript or build process necessary. Just throw your hex value into the --color_primary-hex: variable within the CSS html{} element, play around and have fun.
More on relative color functions and how they work in CSS can be read here: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_colors/Relative_colors
This is an open-source project, opened for personal and commercial use. For any problem or question, just drop me a line at avin@avinvadas.com